Process for vulcanizing rubber and products obtained thereby



Patented Jan. 2, 1923.

UNITED STATES PATENT OFFICE.

SIDNEY M. CADWELL, OF LEONIA, NEW JERSEY, ASSIGNOR TO THE NAUGATUCK CHEMICAL COMPANY, A CORPORATION OF CONNECTICUT.

PROCESS FOR VULCANIZING RUBBER AND PRODUCTS OBTAINED THEREBY.

ll'o Drawing. Original application filed April 1, 1922, Serial No. 548,826. Divided and this application filed April 1, 1922.

To all whom it may concern:

Be it known that I, SIDNEY M. Canwnnn,

a citizen of the United States, residin at Leonia, county of Bergen, and State of ew 5 Jersey, have invented certain new and useful Improvements in Processes for Vulcanizing Rubber and Products Obtained Thereby, of whichthe following is a full, clear, and exact description.

This invention relates to vulcanizing rubber and similar materials and products obtained thereby, being more particularly directed toacceleration of vulcanization by a class of organic accelerators and products resulting from such vulcanization.

This case is a division of application Serial No. 548,826 filed April 1, 1922.

One object of the invention is to provide a process of the kind mentioned employing accelerators obtainable from inexpensive raw materials by a simple method. Another object of the invention is to provide a process in which accelerators of the kind mentioned may be readily compounded with rubber, or similar material, w ich shall permit of the carrying out of vulcanization at ordinary temperatures, in masses of rubber or in thin sheets, while avoiding the generation of acids during the process of vulcanization, as, for'example, takes place when sulphur chloride is used. Another object is to rovide a series of products having genera 1y desirable physical characteristics, such as high tensile strength, resistance to ageing, resistance to flexing, shall be substantially free from the odor of the vulvanizing ingredients employed. Other objects will in part be obvious and in qplart pointed out hereinafter.

e invention accordingly consists broadly in the process, and product obetc., and which Serial No. 548,827.

tained therefrom, for treating rubber and similar materials, which comprises subjecting the rubber to a vulcanizing agent and a substance containing the radical RCSM,

and vulcanizing the rubber. In this formula, R represents any element subject to the limitation mentioned hereinafter; represents a salt-forming element or group or hydrogen, such as zinc, ammonium, etc., and is designated as representing a metal or being metallic, or a radical see or a radical RCSM is limited to any element except nitrogen; in the third group where M represents this limitation is absent. In the table herein shown forming part of the specification, there is shown th broad group containing the radical 80 new sub-divided into threesmaller groups which are respectively RCSM, RCSSCR, RCSCR.

M=Metal, M=SCR M-CR etc.

It will be noted that the group formulae represent generall derivatives of carbon oxvsulphide or car on disulphide.

he formulae of the first two groups mentioned, in which the first symbol R is any element except nitrogen, may be written a'osm,

under which fall R'CSM,

where M is the metal and thiol salts are included, and

where M is equal to SCR and the disulphides are represented. R in these formulae designates any element except nitro en.

In emp oying the first group of those mentioned above including substances having the formula I where M represents one of the preferred metals given. M may be substituted by any metal provided tha one f t e me als understood that just mentioned is present in the combination either at some other position in the formula including season and RGSCR constituting respectively the disulphide and inonosulphide groups, the presence of zinc or mercury in the mercuric state is preferable when vulcanization at ordinary temperatures is carried out. When vulcanization above ordinary temperatures is carried out the preferred metals are the following:zinc, mercury, preferably in the mercuric state, lead, preferably in the plumbous state, cadmium, copper, preferably in the cupric state, arsenic, preferably in the arsenous state, manganese, preferably in the manganous state. 'As noted in-connection with the first group, the metals employed with groups two and three may be present in any combined form.

In the table mentioned above, R and X are shown as represented by carbon, oxygen, nitrogen and sulphur, which are four of the more important elements occuring in organic compounds.

It will be understood that the invention is not limited to the species shown in the accompanying table, and that by substituting other elements than nitrogen, carbon, oxygen and sulphur for the symbol R or X, various other s ecies may be formulated fallingwithin t e scope of the invention.

Although the various species disclosed are represented as symmetrical, it will be unsymmetrical species also fall within the limits of the invention.

The table is:

as follows :-The acceleration by aliphatic GROUP I.

RCBM

M Metal 'Tlflol salts In general, it is to be noted in connection with this group, that its members are able to accelerate both hot vulcanization, that is vulcanization at or above 240 F., and vulcanization below such temperatures, and that they may be used for such vulcanization in thick masses of rubber, in thin sheets, or in cements.

The general procedure for vulcanizing employing members of this group is as follows :100 parts of rubber, 10 parts zinc oxide, 3 parts of sulphur, and 0.1-3.0 parts of accelerator are mixed. If vulcanization is employed the usual temperatures or lower may be used for periods of thirty minutes or more to complete vulcanization. The normal or usual tem eratures for hot vulcanization are 240 or above. If cold vulcanization with heat is desired the mixed materials may be allowed to stand at ordinary room temperature for a week or less, when vulcanization is complete. The pro cedure given above may be employed with thin or thick masses of rubber, and in the case of cements where a solvent is used with the mixture, the rocedure after mixing and evaporation 'o the solvent, is substantially identical with that employed for thin masses of rubber. The use of materials of this group, in the manner indicated above, will secure cold vulcanization without added bases or amines, but -if such bases or amines are added, the vulcanization is accelerated.

The action of the addition of amines to materials of this class has been found to be amines is greatest when approximately a half molecular weight of the amine on the basis -of the carbon disulphide content of the thiol salt is used. An excess of primary aliphatic. amine retards the cure considerably. An excess of secondar aliphatic amine retards the cure less an an excess of tertiary aliphatic amine has practically no retarding effect. The greater the amount of primary aromatic amine added the greater the acceleration. Dibenzyl amine has given excellent results in the acceleration of vulcanization according to the invention. sults. Bases such as sodium hydroxide also accelerate the action of thiol salts.

The thiol salts are particularly adapted to be used in connection with cold curin and cements. It will be understood 0 course as pointed out above that theymay he used in hot vulcanization and otherwise as desired. The members of the group are preferably employed with substances containing combined mm: preferably zinc oxide,

Aniline has also given good reor one of the metals in combination hereinbefore enumerated. The oxides are generally deslgnated at M'O.

Species 1.

As a specific embodiment of one of the members of this group which when employed in'a process constituting the invention has provided good results, the following example is cited :100 parts of rubber, 10 parts of zinc oxide, 4 parts of zinc butyl xanthogenate, 1 part of sulphur, and two (2) parts paratoluidine, are mixed by milling in the usual way. The mixture is milled or sheeted or formed in any other way and the material-so treated is allowed to stand for severaldays. vulcanization is then completed at ordinary temperature without the application of heat. A convenient method for vulcanization at temperatures below 240 F. consists in exposmg the above mixture, milled, sheeted, or formed in any other way desired, to a temperature of approximately 170 F. for 60 minutes, whereupon satisfactory vulcanization issecured. It will be observed that a base, paratoluidine, has been employed here. Such a base, particularly an amine accelerates the vulcanization process, employing the various members of this species, even more rapidly, although if omitted vulcanization will take place at ordinary temperatures. A convenient method for forming molded goods is to heat the rubber compounded with a member of this species for a short period in the mold, and then allow vulcanization toprooeed at ordinary temperatures.

In employing material of this species with cement, the following procedure may be carried out :-100 parts of rubber, 10 parts zinc oxide, 6 parts of zinc butyl xanthogenate, are made into a cement with 800 parts of benzol; and 100 parts of rubber, 10 parts of zinc oxide, 6 parts of sulphur and 6 parts of paratoluidine are made into cement with 800 parts of benzol. Neither one of these cements will vulcanize at orperatures are employed vulcanization pro ceeds more quickly.

, Zinc butyl xanthogenate is prepared as follows: 20 lbs. potasium hydroxide sticks are dissolved in a minimum amount of hot water. The solution is cooled and laced in a cool tub, and 6000 cc. carbon disulphide and 7000 cc. butyl alcohol are slowly added with stirring and cooling. Heat is evolved and the reaction mixture takes on ared color. It is cooled and filtered and the residue which is believed to be potassium butyl xanthogenate is recrystallized from a small amount of water. 200 grams of this potassium butyl xanthogenate are dissolved in a litre of water and added to 200 grams of zinc sulphate dissolved in a litre of water. The precipitate which forms is believed to be zinc butyl xanthogenate. It is filtered out and dried at ordinary temperature. The zinc butyl xanthogenate as thus prepared usually contains a small amount of zinc oxide, but it may be purified until only a small per cent zinc oxide remains. Among its properties may be mentioned the following It decomposes in the presence of amines and alkalies. It isawhite powder;it is soluble in about 10 parts benzol, soluble in about 8 parts chloroform, somewhat soluble in carbon tetrachloride, slightly soluble in gasoline or ligmm.

In general, members of this species operate advantageously Where the zinc or similar combined metal is present. Where zinc oxide is used reduction in its proportions will produce transparent stocks.

Other members of this species falling under the general formula given are butyl xanthogenate of potassium, sodium, barium, magnesium, calcium, ammonium, iron, lead, etc.

Other members of this species are Barium ethylxanthogenate Sodium methylxanthogenate cinocsna Lead methylxanthogenate CH OCSPbSCOCH Zinc methylxanthogenate CH OCSZDSCOCH Lithium ethylxanthogenate canocsm Magnesium ethylxanthogena'te cmsoosu scooinb Calcium ethylxanthogenate CgHgOCBCBBCOQHa Ammonium ethylxanthogenate emotions.

Potassium ethylxanthogenate cimocsx Sodium ethylxanthogenate cnnoosm Ferric ethylxanthogenate C1H5OCBF03 Lead ethylxanthogenate (limocsrbsoocata Mercuric ethylxanthogenate oimocsn scocni5 U Potassium amylxanthogenate cu ocsiz Zinc amylxanthogenate C5H 0CSZnSCOH C5 Zinc ethylxanthogenate oinfiocsznsconfic,

Species ocsM The following members of this species have been employed to give good results in connection with the process included in the invention CaHaOG-SK Ethyloxyester of potassium thiolcarbonate (hH OO-SK Butyloxyestor of potassium thioicarbonate Ethyl ester of phenylthiocarbamic acid Butyl ester phenylthiocarbemic acid 192960568 5. GOSH The following members of this species have been employed to give good results in connection with the process included in the invention:

Lead dithiophenylacetate Lead dithiobenzoate 0 11 0-18 PbS-GOJB Zinc dithiobenzoate qmo-szus co.n,

Cadmium. dithiobenzoate or y Mercurous dithlobenzoate Cuprie. dithiobenzoate o,H,o scus-0C m Potassium dithiobenzoate (LG-SK Lead dithioacetate omo-srbs-cos.

Lead dithiobrombenzoate BrQ H4OSPbSCC H Br Zinc dithiobenzoste is preferably employed as follows: 100 parts of rubber are mixed with 10 arts zinc oxide, three parts sulphur, and and vulcanization is accomplished in a mold under in) lbs. steam pressure for 30 minutes.

part zinc dithiobenzoate,-

Species The following members of this species have been employed to give ood results in connection with the process included in the The following members of this species have been employed to give good results inconnection with the process included in the invention UHb NHg Thlobenzamlde." 9 5 n a sHo Thiobenzanfllde.

Species 9.

The following members of this species have been employed to give good results in connection with the process included in the invention 2-- cgfifioafflllak Cobalto ammonium trlt iocarhonatc. K. A. Hoffman 8: Hochtlen Berlchte 36, 1146 (1903).

GBuGuNIL 1 10 Cuproammoniumtrithiocarbonate (same ref.)

KI Ba Potassium trlthiocarbonate.

Ca (OHhCaCS: Basic calcium trithiocarbonate.

Species 10.

seen

The following member of this species has beenemplo ed to give good results in connection wit the process included in this invention:

- ZnGOEl y Zinc dithlocarliomte.

, Species 13.

nosn

The membrs of this dlass include:

Ammonium para aminophenylenedithiocarbamate -nnmamnwsum Ammonium phenylethyldithiocarbamate Potassium para.-aminophenylenedithiocarbamate p-N lmamrm-o-sx Zinc para. aminophenylenedithiocarbamate -NH,0,H4NHc-szn-scNH0.mN 11,-

Zinc ethylphenyldithiocarbamate CIHQ 05H: C2K|s i j CflL Ammonium benzidyldithiocarbamate Ammonium phenyldithiocarbamate cJLNHHNm Zinc alphananthyldithiocai'bamate Paramethylphenyleneammonium methylphenylenedithiocarb amate para- Ammonium metamethylaminophenyldithioc arbamate Ammonium paranitropheny'lenedithiocarbamate bNo cnnmno-sun.

bamate Ammonium paramethylphenylenedithi0- 66 orthomethylphenylenedithi0- c arbamate Zinc paramet'nyl pnei'l y'lenedithiecarbamate -cmcmmBc-sznscNHmmcm- Ammonium orthomethylphenylenedithiocarbamate Zinc phenylethylthiocarbamate N-0-s-zn-s-c-N Ca n/ 15 Zinc phenylmethyldithiocarbamate \Ce a Stannous pai'amethylphenyienedithiocarbamate Iron phenyldithiocarbamate C H NHCL-SF Zinc phenyldithiocarbamate C H NHlC-S-Zn,

Iron ethylphenyldithiocarbamate NC-SFe; Cum

Barium ethylphenyldithiocarbamate Calcium ethylphenyldithiocarbamate Para aminophenyleneammonium paraaminophenylenedithioc arbamate Barium Zinc mate

0ithomethylphenylenedithiocar- 0rthomethylphenylenedithiocarba- Ferrig paramethylphenylenedithi0carbamate Copper ethylphenyldithiocarbamate Zinc methylphenyldithiocarbamate Species 14.

The following member of this species has been employed to give good results in connection with the process included in this invention Zinc 'diethylthiocarbamate Species 15. NCBM The following members of this ecies have been employed .to give good resu ts in connection with the process included in this 1nvent1on:-

Ethylphenylthiourea 00H Dimethylphenylthiourea (GHahNCr-SH It will be understood that the invention disclosed in co-pending application Serial No. 441,691, filed February 1, 1921, ma be employed in connection with the acce erators disclosed and included in the invention of the present application. 7

It 18 to be understood that rubber sub stitutes synthetic rubber, balata, tta percha, etc., may be similarly treate instead of rubber and it is intended to cover such processes in the claims.

In general the accelerators included in Group I given above are obtainable from inexpensive raw materials by simple metheds. The members of the group may be readily compounded with rubber or similar -vulcanization in thin or thick masses of rubber or in cements. It will be particularly noted that the members of Group I are able to accelerate vulcanization at temperatures below the normal vulcanizing temperature, for instance at ordinary room temperature. The ability to vulcanize at such temperature varies somewhat in accordance with the species selected. ,v

The products obtained provide in general desirable physical characteristics, such as high tensile strength, resistance to ageing, resistance to flexing, etc, and in general are e free from the .odoi; of vulcanizlng ingredients. It will -thus be seen that among others the objects of the invention above enumerated are achieved.

As many apparently widely different embodiments of this invention ma be made. without departing from the s 'rit thereof, it will be understood that I 0 not intend to limit myself to the specific embodiment: herein set forth except as indicated in'the appended claims. 7 ach of the substances enumeratd herein as members of the various species has been employed in the vulcanization of rubber and has been found to accomplish vulcanization as indicated.

Having thus described my invention, what I claim and desire to protect by Letters Patent is:

1. A process of vulcanizin rubber or similar material which comprises combin- 100 ing with the rubber a vulcanizing agent and an accelerator comprising the group where M is a metal, and vulcanizing the m rubber.

2. A process of vulcanizing rubber orsimilar material which comprises COHlblIling with the rubber a vulcamzing agent and an accelerator comprising the group Rosa,

and vulcanizing the rubber.

3. A process of vulcanizing rubber or similar material which comprlses combining with the rubber a vulcanizing agent and an accelerator comprising the group RGSM,

where M is a metal, and vulcanizing the rubber at a temperature below the normal I hot vulcanizing temperature. 4. A process of vulcanizing rubber or 12 similar material which comprises combining with the rubber a vulcanizing agent and an accelerator comprising the group nosm',

and vulcanizing the rubber at a temperature below the normal hot vulcanizing temperature.

5. A process of vulcanizing rubber or similar material which comprises combining with the rubber a vulcanizing agent and an accelerator comprising the radical Where M is a metal, and vulcanizing the rubber.

6. A process of vulcanizing rubber or similar material which comprises combining the rubber with a vulcanlzing agent and an accelerator comprising the radical ocsn',

- and vulcanizing the rubber.

7. A process of vulcanizing rubber or similar material which comprises combining the rubber with a vulcanizing agent and an accelerator comprising the radical and vulcanizing the rubber at a temperature below the normal hot vulcanizing temperature.

. 8. A process of vulcanizing rubber or Similar material which comprises combining with the rubber sulphur and an accelerator comprising the group mean,

where M is a metal, in the resence of a combined metal M, and vu canizing the rubber.

9. A process of vulcanizing rubber or similar material which comprises combining with the rubber sulphur and an accelerator comprising the group and vulcanizing the rubber.

10. A process of vulcanizing rubber or similar material which comprises combining with the rubber sulphur and an accelerator comprising the radical ocsir,

and vulcanizing the rubber at a temperature below the normal hot vulcanizing temperature.

11. The process of treating rubber or similar material which comprises combinin it with a vulcanizing agent, an amine an a metallic xanthogenate, and vulcanizing the rubber.

12. The process of treating rubber or similelrmaterial, comprising combining it thogenate, and an amine, and vulcanizing the rubber at a temperature below the normal hot vulcanization temperature.

15. A vulcanized rubber derived from rubber combined with sulphur, a metallic butyl Xanthogenate, an amine, and zinc oxide.

16. A vulcanized rubber derived from rubber or similar material combined with a 'vulcanizing agent and an acceleratorcomprising the group RCSM,

where M is a metal.

17. A vulcanized rubber derived from rubber or similar material combined with a vulcanizing agent and an accelerator comprising the group RCSM',

18. A rubber vulcanized at a temperature below the normal hot vulcanizing temperature derived from rubber or similar material combined with a vulcanizing agent and an accelerator comprising the group n'psu,

where M is a metal.

19. A rubber vulcanized at a temperature below the normal hot vulcanizing temperature derived from rubber or similar material combined with a vulcanizing agent and an accelerator comprising the group now.

20. A vulcanized ,rubber derived from rubber or similar material combined with a vulcanizing agent and an accelerator comprising the radical ocsn where M is a metal.

21. A vulcanized rubber derlved from rubber or similar material combined with a vulcanizing agent and an accelerator comprising the radical ocsu'.

22. A vulcanized rubber derived from rubber or similar material combined with sulphur and an accelerator comprising the group RCSM,

where M is a metal, in the presence of a combined metal M.

23. A rubber vulcanized at a temperature below the normal hot vulcanizing temperature derived from rubber or similar material combined with a vulcanizing agent and an accelerator comprising the radical 24. A vulcanized rubber derived from rubber or similar material combined with sulphur and an accelerator comprising the group R'psM'.

25. The step in the process of vulcanizing rubber comprising combining it with a 1116- tallic butyl Xanthogenate.

26. The step in the process of vulcanizing rubber at low temperatures comprising combining it with a metallic butyl xanthogenate.

27. The process of vulcanizing rubber comprising combining it with sulphur, a metallic butyl xanthogenate, and zinc in combination.

28. The process of vuleanizing rubber which comprises combining it with sulphur, metallic butyl xanthogenate, and zinc in combination and vulcanizing it at approximately 70 i 29. The process of vulcanizing rubber at a temperature below the normal hot vulcanization temperatures comprising combining it with sulphur, zinc butyl xanthogenate, and zinc in combination.

30. The process of vulcanizing rubber at a temperature below the normal hot vulcanization temperatures comprising combining 1t with sulphur, zinc butyl xanthogenate, paratoluidine, and zinc oxide.

31. The process of vulcanizing rubber at a temperature below the normal hot vulcanizatmn temperatures comprising combinmg 1t with sulphur, a metallic butyl xanthogenate, an amine, and a metallic oxide.

32. The process of vulcanizing rubber at a temperature below the normal hot vulcanrzation temperatures comprising combinmg it with sulphur, zinc butyl xanthogenate; an amine, and zinc in combination.

33. The process of vulcanizing rubber compr sing combining it with sulphur, a metallic butyl xanthogenate, an amme, and zinc oxide.

34. The step in the process of vulcanizing rubber comprising combining it with a metallic salt of the caustic alkali, and butyl alcohol.

35. The step in the process of vulcanizing rubber at low temperature comprising combining it with the zinc salt of the reaction product of carbon bisulphide, potassium hydroxide, and butyl alcohol.

36. A vulcanized rubber-like material derived from rubber or similar material combined with a metallic xanthogenate and an amine.

37. A vulcanized rubber derived from rubber or similar material combined with sulphur, and amine and a metallic xanthogenate.

38. A vulcanized rubber derived from rubber or similar material combined with a vulcanizing agent, a metallic xanthogenate, and an amine.

39. A rubber vulcanized at a temperature below the normal hot vulcanization temperature, derived from rubber or similar material combined with a vulcanizing agent and a metallic xanthogenate.

40. A rubber vulcanized at a temperature below the normal hot vulcanization temperature, derived from rubber or similar material combined with avuleanizing agent, a metallic xanthogenate, and an amine.

41. A rubber vulcanized at a temperature below the normal hot vulcanization temperatures, derived from rubber combined with sulphur, a metallic butyl xanthogenate, and zinc oxide.

42. A rubber vulcanized at a temperature below the normal hot vulcanization temperatures, derived from rubber combined with sulphur, zinc butyl xanthogenate, and zinc oxide.

43. A rubber vulcanized at a temperature below the normal hot vulcanization temperatures, derived from rubber combined with sulphur, zinc 'butyl xanthogenate, paratoluidine, and zinc oxide.

44. A rubber vulcanized at a temperature below the normal hot vulcanization temperatures, derived from rubber combined with sulphur, a metallic butyl xanthogenate, an amine, and a metallic oxide.

45. A rubber vulcanized at a temperature below the normal hot vulcanization temperatures, derived from rubber combined with sulphur, zinc butyl xanthogenate, an amine, and zinc oxide.

46. A rubber vulcanized at a temperature below the normal hot vulcanizing temperature derived from rubber or similar material combined with sulphur and an accelerator comprising the radical celerator which is a carbon bisulphide addition product of liutyl alcohol.

48. The process ofaccelerating the vulcanization of a composition containing a plastic gum and a vulcanizing agent which comprises vulcanizing the composition together with a metallic salt of butyl xanthogenate.

=49. The process of accelerating the vul- 10 canization of a rubber composition which comprises vulcanizing the composition together with a zinc butyl xanthogenate vulcanization accelerator.

50. The process of manufacturing a lowtemperature vulciinizimg composition which comprises milling together rubber, sulphur, and a metal normal butyl xantliogeniite.

Signed at New York, New York, this 30th clay of March, 1922.

SIDNEY M. (JADWELL.

.elaim 18, in the formula. insert an 'a: below'thp doublebon Certificate of Correction.

Patent No. 1,440,963. Granted Ja nuar y 2, 1923, to

V SIDNEY M. CADVVELL. It is hereby certified that error appears in the printed specification of the abovenumberetl patent requiring correction as follows: Page 1, lines 59 and 60, strike out the formula and insert instead v page 2, lines 29 and 23, strike out the formula and insert n'csscn;

page 3; in the table Group III, species 40, strike out the formula and insert instead CC 8 C0;

\ II: III page 4, line 18, after-the Wm'li vulcanization insert the words with heat, and line 24, strike out the words with heat; same page, line 68, for the word at read as; page 5,.lines 119 to 123, strike out the formula and insert instead I Hh-Cll-ClhNll' ==s Cami page 6, lines 21 to 23, strike out the formula and insert same page, lines 82 to 87, strike out the two formulas and insert instead ClHtO-BPbfl-dOIHY Species 9'.

com

a page 7, lines 83 to 85, strike out the formula and insert page 5, line 73, a 7 lines as, 91, 95,'100, 105, 10,9 M1126 and a 8, lines 3,. 1 1 22, ans s, iii the formulasiusertn diagonal dash hetwee n 518B subscript numerals, and the symbols for the metals of the compounds; age 9, line 104, d p e 10, line an that the said Letters Patent should be read with these corrections therein that the same may m WM. A. KINNAN,

Acting Gammim'oner of Patents. 

